1. Field of the Invention
The present invention relates to a battery monitoring system and a battery monitoring device.
2. Description of the Related Art
Generally, as large capacity, high output batteries such as those employed in hybrid vehicle and electric vehicle motor drives, batteries are employed that are configured for example from plural battery cells, such as lithium ion battery cells, connected together in series so as to configure groups. Since such batteries have large capacities and high outputs, there is strong requirement to quickly detect states such as rapid voltage fluctuations that occur in battery cells for one reason or another, and to quickly and safely stop the operation of circuits and the like operated by the battery. Monitoring of battery voltages in plural battery cells is accordingly performed by plural battery monitoring devices.
A related battery monitoring system has respective circuits that are operably on power source supply from battery cell groups provided within each of plural installed battery monitoring devices, generally in a configuration in which the voltage of each respective battery cell group is measured by plural battery monitoring devices. However, with such battery monitoring systems, there are occasions when it is not always necessary to monitor the voltage of battery cells, such as circumstances in which the vehicle is not being driven, or in situations when parked with the engine not running.
However, the battery cell groups and the battery monitoring system are always electrically connected to each other, and since this is a state in which the voltage from the battery cell groups is being applied to the battery monitoring system, the voltage of the battery cells is always in a monitored state in the related battery monitoring system. Such a situation is not preferable from the perspective of power consumption.
Thus, in order to suppress power consumption of a battery monitoring system, for example as described in Japanese Patent Application Laid-Open (JP-A) No. H08-140204, although the battery cell groups and the battery monitoring system are always electrically connected to each other, a mode referred to as a sleep mode is provided, and the functions and operation of internal circuits operated by voltage supplied from the battery cell groups are stopped when not required.
In another field, for example in JP-A No. 2006-180486, technology is also described for stopping driving of a regulator during a sleep mode in order to achieve a reduction in power consumption.